How do I Manage My Objects/Layouts More Efficiently

So I've come to a point where the final decision is to build on multiple layouts vs one huge layout.

What I'm struggling to get my head around is the best way to manage my objects in terms of multiple layouts that use common assets/objects. Research has given me Global Objects and Global Layers. Neither of which seem to work in this case. Essentially I'd like all the objects to be available on every single layout regardless of layers or it being duplicated from the initial layout.

Also I get the feeling that I'm being a massive noob, creating the same four-five layers on ever single new layout..

you can create 1 layout "objects" and toss all there instead of throwing objects all over in and outside of layouts and simply spawn objects via events in the "normal" layouts.

you can use effects like adjust HUE to have many variations of 1 object instead of creating multiple objects.

you can use 1 master event sheet with all rules that can apply to all and then use the include event sheet for each dedicated layout. This allows the dedicated layouts (e.g. level 1, level 2) to have very clean event sheets with only special rules which are special only to that layout.

you can learn about automatically / randomly generating gaming area to avoid building multiple layouts and instead use the event sheet to dictate the parameters of the generation (i still need to learn this myself )